1. Field of Invention
This invention relates to carburetors and more particularly to carburetors provided with acceleration pumps.
2. Prior Art
In carburetors provided with prior art accelerating pumps, a satisfactory quantity of fuel is supplied at the first stage of rapid acceleration to improve the response of the engine to acceleration. However, the time during which fuel for acceleration is supplied as short. Since the time during which fuel for acceleration is supplied is short, during the time from the completion of the supply of fuel for acceleration to a stabilized condition of supplying fuel from a fuel feed port the air fuel mixture taken into the engine is lean. Since during this time the air fuel mixture is lean, it becomes difficult to smoothly accelerate the engine. In particular, when the engine is cold, this tendency is increased.
To obviate this drawback, in the prior art steps have been taken to extend the stroke of the piston of the accelerating pump. This solution improved the driveability of the engine when it is cold. However, when the engine is hot, during the initial stage of acceleration the mixture becomes excessively rich. Therefore, the engine experiences a disadvantageous condition called a hunting phenomenon.